(1) Field of the Invention
The present invention relates to an optical disk apparatus and a test writing method for recording data onto an optical disk, and particularly to a technique for performing test writing with high accuracy.
(2) Description of the Related Art
In an optical disk apparatus, when a laser beam is irradiated onto an optical disk to record data, a laser power is adjusted so that the data is recorded with a power suitable for characteristics of the optical disk and environment in which the optical disk is used. The adjustment of the laser power is called OPC (Optimum Power Control). The OPC allows a test signal whose laser powers are changed stepwise to be recorded for test writing at test writing areas on the disk, and the signal is reproduced so that the quality of the reproduced signal, e.g., β (asymmetry) and the like are assessed, to thereby set the laser power with which target β can be obtained, as the optimum recording power. The process of optimizing recording conditions when recording data as described above is hereinafter referred to also as recording condition learning. It should be noted that not only the adjustment of the laser power, but also the adjustment of timing of laser power changes is performed in the recording condition learning in some cases. Therefore, the recording condition learning, together with the above-described OPC is hereinafter referred to also as test writing.
However, when some defects and the like are present at the test writing areas on the optical disk, the recording condition learning is not properly performed. As a result, the optimum recording condition cannot be obtained, or even if the optimum recording condition can be obtained, the obtained condition is out of the range of a correct condition, which causes a trouble in subsequent data recording. In order to execute the test writing while skipping such defects on the disk, the following techniques are proposed.
Japanese Patent Application Laid-Open No. 2005-182886 discloses a technique in which a test writing management area is provided on an optical disk, information about test writing areas (location information about areas where deterioration or defects of a film surface are present, information about a state of the film surface, and the like) is recorded in the test writing management area, and test writing is executed while skipping the areas where the deterioration or defects are present on the basis of the information.
Japanese Patent Application Laid-Open No. 2002-319135 discloses a technique in which an optical disk with no data being recorded is played in advance, physical states (flaws, fingerprints and the like on a recording surface of the optical disk) of areas where data is recorded are detected by using an obtained signal, and the locations where the flaws, fingerprints and the like are detected are excluded from targets to be assessed, so that data recording can always be performed on the optimum condition irrespective of the physical states such as the flaws and fingerprints on the optical disk.